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TPS62150: Radiation noise

na na78
Guru 16770 points
Part Number: TPS62150
Other Parts Discussed in Thread: TPS562200, , TPS62147, TPS62148

Hi

We are evaluating TPS62150EVM-505 and facing problem of unwanted radiation noise.

Measured noise is attached in following file.

Input : 9V

Output : 3.3V/0.4A

5861.e2e.xlsx

You can see radiation noise at 300MHz -400MHz with TPS62150EVM.

As comparison, measurement result of TPS562200 is also attached. 

Radiation noise was not observed with TPS562200.

Why is the radiation noise occurred with TPS62150EVM?

Could you please tell me how to avoid or suppress radiation noise?

BestRegards

  • 0
    TI__Genius 14876 points
    Hello,

    Could share with us your test set up? I don't really understand what I am looking at, it seems you are doing a frequency sweep analysis of the system.

    TPS62150 is not the most recent device. I also recommend you have a look at the newest devices which are TPS62147/TPS62148.

    Thank you very much!
    Best Regards,

    Dorian
  • 0 in reply to Dorian Brillet de Cande
    Guru 16770 points

    Hi

    Lem me explain the test set up.

    e2e_v2.xlsx

    Please see Sheet1.

    INSTRUMENT:ESV-3000 from NOISE LABORATORY

    This can be used for electromagnetic wave analysis and

    it can visualize noise source on the board.

    (It is represented like heatmap on board surface)

    RED mapped area means that the noise is emitted the most and

    it is around TPS62150. RED mapped area is corresponding to A.

    In addition, same result is obtained by using spectrum analyzer(B).

    So we doubt if TPS62150 circuit would be noise source.

    In Sheet2, result of other measurement is attached.

    It shows noise with every load current.

    According to result, noise level is decreased if output current is 300mA

    while with other output current level leads to emit noise.

    (Input =12V, with this test)

    Our customer designed custom board using TPS62150.

    This noise issue is discovered with customer's board first.

    That why we tested same analysis using evaluation board to confirm

    if same noise appears.  In result, it was the same.

    So, Could you please make it clear why TPS62150EVM emit the noise

    at 300MHz-400MHz? Could it be caused of layout?

    BestRegards

  • 0 in reply to na na78
    TI__Genius 14876 points

    Hello,

    I found an previous E2E thread in which this topic was already discusssed:

    https://e2e.ti.com/support/power-management/f/196/t/411527?tisearch=e2e-sitesearch&keymatch=TPS62150

    In this App Note you can find how to minimize ringing with snubber for Boost Converter, it can also be applied to Buck-Boost:

    http://www.ti.com/lit/an/slva255/slva255.pdf

    Thank you!

    Best Regards,

    Dorian

  • 0 in reply to Dorian Brillet de Cande
    TI__Genius 14876 points
    Hello,

    I haven't heard back from you. Did the other E2E thread and App Note helped you to solve your queries?
    Thank you very much!

    Best Regards,
    Dorian
  • 0 in reply to Dorian Brillet de Cande
    Guru 16770 points
    Hi Dorian

    I'm sorry for late reply.

    The information you suggested would help us with this issue.

    Let me confirm EMI of TPS62150EVM.

    TPS62150EVM would offer recommended circuit and layout, however, it is not optimized for EMI.
    So we should take additional provision of EMI even if they refer evaluation boards if needed.
    Is my understanding correct?

    BestRegards
  • 0 in reply to na na78
    TI__Genius 14876 points

    The EVM is not optimized for good EMI performances. To show better EMI results we tend to rework the boards. Higher noise in this region is very typical for this device. It can be mitigated by adding a small 0402 capacitor close to the device at the input PVIN/PGND and of course route it with low impedance connections.

    Looking at the frequency characteristic I would recommend to use a 470pF capacitor:

    This can also help you

     

    The important thing is to design a decoupling/filter capacitor structure with an appropriate bandwidth. You can compare impedance charts of different capacitors for their impedance at the critical frequencies. What you finally need to do is selecting a combination of capacitors to get the low impedance over frequency needed or just find something which has lower impedance in the critical frequency range compared to the existing solution which needs improvement. Here are some pictures related to that:

    Thank you very much!

    Best Regards,

    Dorian

  • 0 in reply to Dorian Brillet de Cande
    TI__Genius 14876 points
    Hello,

    I haven't heard back from you. Were these explanations useful for your understanding? Do you have any follow up questions?
    Thank you very much!

    Best Regards,
    Dorian
  • 0 in reply to Dorian Brillet de Cande
    Guru 16770 points
    Hi Dorian

    Thank you for your reply.
    Adding snubber and input capacitance to EVM led to decrease 300MHz - 400MHz noise but increasing noise at 30MHz - 100MHz.

    It might be caused of layout. The customer might to re-work their layout or EMI.
    I will continue to support customer but the update and feedback to you would be after finishing re-work their boards.
    So I will close the thread in this time and will open new thread if I had additional questions.
    Thank you for your cooperation.

    BestRegards